Rotating electric machine and method for manufacturing the rotating electric machine

ABSTRACT

A rotating electric machine includes: a stator core having a plurality of slots aligned along a circumferential direction; a stator having a stator coil with an enamel coating inserted into the slots of the stator core; and a rotor rotatably arranged over the stator core through a given gap. The stator coil includes: main coils of a plurality of phases in which a plurality of segment coils each having a rectangular cross-section wire formed into a substantially U-shaped wire in advance is connected to each other; a first sub-coil having a lead wire led from the slots and attached with an AC terminal, and connected to one end of the respective main coils; and a second sub-coil having a neutral wire led from the slots, and connected to the other end of the respective main coils. The lead wire and the neutral wire are each formed of a wire with a bend structure having a plurality of straights and bends.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of and claims priority to U.S. patentapplication Ser. No. 14/239,729, the entire disclosure of which isincorporated herein by reference, which entered into the U.S. nationalphase, on Feb. 19, 2014, as a 371 of International Application No.PCT/JP2012/070247, filed Aug. 8, 2012, the entire disclosure of which isalso incorporated herein by reference, which claims priority to JapanesePatent Application No. 2011-207403, filed Sep. 22, 2011, the priority ofwhich is also claimed here.

TECHNICAL FIELD

The present invention relates to a rotating electric machine, and amethod for manufacturing the rotating electric machine.

BACKGROUND ART

In the rotating electric machine, an AC power is supplied to a statorcoil to generate a rotating magnetic field, and a rotor is rotated bythe rotating magnetic field. Also, a mechanical energy applied to therotor can be converted into an electric energy to output the AC powerfrom the coil. In this way, the rotating electric machine operates as anelectric motor or an electric generator. As a stator of the rotatingelectric machine of this type, there has been known a configuration inwhich an external connection side lead wire is arranged on an upperportion of a stator core so as to extend in an axial direction, and aneutral wire is arranged on each end of the external connection sidelead wire (for example, refer to Patent Literature 1).

CITATION LIST Patent Literature

Patent Literature 1: Japanese Laid-Open Patent Application No.2011-015459

SUMMARY OF INVENTION Technical Problem

When the rotating electric machine of this type is mounted in a vehicle,the rotating electric machine is downsized to be downsized because therotating electric machine is attached to a limited small space. In orderto ensure a gap between an upper portion of a coil end and an emissionportion, it is desirable to narrow a convex area where the neutral wireis routed. However, the rotating electric machine of this type suffersfrom such a problem that a core back or the coil end becomes large, andis protruded in an axial direction or a radial direction.

Solution to Problem

According to one embodiment of the present invention, there is provideda rotating electric machine including: a stator core having a pluralityof slots aligned along a circumferential direction; a stator having astator coil with an insulation coat inserted into the slots of thestator core; and a rotor rotatably arranged over the stator core througha given gap, in which the stator coil includes: main coils of aplurality of phases in which a plurality of segment coils each of themare formed from rectangular cross-section wire into substantiallyU-shape in advance is connected to each other; a first sub-coil having alead wire led from the slots and attached with an AC terminal, andconnected to one end of the respective main coils; and a second sub-coilhaving a neutral wire led from the slots, and connected to the other endof the respective main coils, and in which the lead wire and the neutralwire are each formed of a wire with a bend structure having a pluralityof straights and bends.

According to another embodiment of the present invention, there isprovided a method for manufacturing the rotating electric machineaccording to the above embodiment, in which a forming process of bendinga wire while abutting a molding pin against the wire is sequentiallyconducted a plurality of times to form a plurality of bends.

Advantageous Effects of Invention

According to the present invention, the core back and the coil end canbe downsized.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic diagram illustrating an overall configuration of arotating electric machine according to a first embodiment of the presentinvention.

FIG. 2 is a perspective view illustrating a stator of the rotatingelectric machine according to the first embodiment of the presentinvention.

FIG. 3 is a perspective view of a stator core 132.

FIG. 4 is a diagram illustrating a magnetic steel sheet 133.

FIG. 5 is a diagram illustrating a cross-section of a rotor 150 and astator 130.

FIG. 6 is a perspective view illustrating a stator coil 138.

FIG. 7 is a diagram illustrating a star connection.

FIG. 8 is a perspective view illustrating a stator coil 138U.

FIG. 9 is a perspective view illustrating a stator coil 138U1.

FIG. 10 is a perspective view illustrating a stator coil 138U2.

FIG. 11 is a diagram illustrating a connection method of a segment coil28.

FIG. 12 is an enlarged view of a portion of a lead wire 500U1illustrated in FIG. 9.

FIG. 13 is a diagram illustrating a forming process of the lead wire500U1 which is viewed from a center side of the stator core 132.

FIG. 14 is a diagram illustrating a forming process of the lead wire500U1 which is viewed along an axial direction thereof.

FIG. 15 is a diagram illustrating a lead wire 500U1 of a U1 phase coiland a lead wire 500U2 of a U2 phase coil.

FIG. 16 is a diagram illustrating a portion of a neutral wire connectionportion 712 in FIG. 6.

FIG. 17 is a diagram illustrating the U1 phase connected to an ACterminal 41U, and a lead wire of the U1 phase.

FIG. 18 is a diagram illustrating neutral wires 712U2, 712V2, and 712W2connected by a neutral wire connection portion 712.

FIG. 19 is a diagram illustrating a connection structure of a statorcoil according to a second embodiment.

FIG. 20 is a diagram illustrating a bridge wire 400U.

DESCRIPTION OF EMBODIMENTS

Hereinafter, embodiments of the present invention will be described withreference to the drawings.

First Embodiment Overall Configuration of Rotating Electric Machine

A rotating electric machine according to this embodiment is a rotatingelectric machine suitably used for travel of the vehicle. In thisexample, as so-called electric vehicle using the rotating electricmachine includes, hybrid electric vehicle (HEV) having both of an engineand the rotating electric machine, and a pure electric vehicle (EV) thattravels only by the aid of the rotating electric machine without usingthe engine. However, the rotating electric machine described below canbe used for both of those types, and therefore a description will betypically given of the rotating electric machine used for the vehicle ofthe hybrid type.

FIG. 1 is a schematic diagram illustrating an overall configuration of arotating electric machine 100 according to a first embodiment of thepresent invention. FIG. 1 illustrates an interior of the rotatingelectric machine 100 with a partial cross-section of the rotatingelectric machine 100. As illustrated in FIG. 1, the rotating electricmachine 100 is arranged within a case 10, and includes a housing 112, astator 130 having a stator core 132 fixed to the housing 112, and arotor 150 rotatably arranged within the stator. The case 10 isconfigured by an engine case or a transmission case.

The rotating electric machine 100 is a three-phase synchronous motorwith an interior permanent magnet. The rotating electric machine 100operates as an electric motor that rotates the rotor 150 with the supplyof a three-phase AC current to the stator coil 138 winded on the statorcore 132. Also, when the rotating electric machine 100 is driven by theengine, the rotating electric machine 100 operates as a power generator,and outputs a generated power of three-phase AC. That is, the rotatingelectric machine 100 has both of a function as the electric generatorthat generates a rotating torque on the basis of an electric energy, anda function as an electric generator that generates an electric power onthe basis of a mechanical energy, and can selectively use the abovefunctions according to a travel state of the vehicle.

The stator 130 is fixed to the housing 112. The stator 130 is fixedlyheld within the case 10 by fastening a flange 115 disposed on thehousing 112 to the case 10 with a bolt 12. The rotor 150 fixed to ashaft 118 is supported by bearings 14A and 14B assembled with the case10, and rotatably held within the stator core 132.

FIG. 2 is a perspective view illustrating the stator 130 fitted to thehousing 112. The housing 112 is formed into a cylindrical shape bydrawing a steel plate (high tension steel or the like) of about 2 to 5mm thickness. An end of the housing 112 in an axial direction thereof isequipped with a flange 115, and fixed to the case 10 with the bolt asdescribed above (refer to FIG. 1). The flange 115 is integrally formedwith the housing 112 by drawing. The stator 130 may be fixed directly tothe case 10 without the provision of the housing 112.

The stator 130 is fixed to an inner peripheral side of the housing 112,and includes a cylindrical stator core 132, and a stator coil 138equipped in the stator core 132. FIG. 3 is a perspective view of thestator core 132. The stator core 132 is formed by stacking a pluralityof magnetic steel sheets 133 as illustrated in FIG. 4 on each other. Themagnetic steel sheet 133 is about 0.05 to 1.0 mm in thickness, andshaped by punching or etching. The stacked magnetic steel sheets 133 arefixed by welding. In an example illustrated in FIG. 3, welded portions200 indicate the welding portion. With such welding, the respectivestacked magnetic steel sheets 133 are connected to each other, and thedeformation of the magnetic steel sheets 133 caused by a tighteningforce in press fitting the magnetic steel sheets 133 into the housing112 is suppressed.

A plurality of slots 420 extending in the axial direction is formed inthe stator core 132 at regular intervals in the circumferentialdirection of the stator core 132. The number of slots 420 is, forexample, 72 in this embodiment. The stator coil 138 is housed in theslots 420 as illustrated in FIG. 2. In the example illustrated in FIG.3, the slots 420 are open slots, and opening is formed in an innerperipheral side of the stator core. A width of the opening in thecircumferential direction is substantially equal to or slightly smallerthan coil loaded portions of the respective slots 420 in which thestator coil 138 is loaded.

An insulating paper 300 is arranged within the respective slots 420. Theinsulating paper 300 is arranged in each of the slots 420, and coil ends140 a, 140 b. The insulating paper 300 (so-called slot liner) arrangedin the slots 420 is arranged between the coils inserted into the slots420 and between the coil and an inner surface of the slot 420. With thisconfiguration, a withstand voltage between the coils and between thecoil and the inner surface of the slots 420 is improved.

Also, the insulating paper 300 arranged on the coil ends 140 a and 140 bis annularly arranged between the coils for phase to phase insulation,or wire to wire insulation at the coil ends 140 a and 140 b. In thisway, the rotating electric machine 100 according to this embodiment canhold a necessary withstand voltage even if an insulation coat of thecoil is damaged or deteriorated, because the insulating paper 300 isarranged on an inside of the slots 420 or the coil ends 140 a, 140 b.The insulating paper 300 is, for example, an insulating sheet of aheat-resistant polyamide paper, and about 0.1 to 0.5 mm in thickness.

Teeth 430 are formed between the slots 420, and the respective teeth 430are integrated with an annular core back 440. The stator core 132 isformed of an integral core in which the respective teeth 430 and thecore back 440 are integrally molded. The teeth 430 operates to guide arotating magnetic field generated by the stator coil 138 to the rotor150, and allow the rotor 150 to generate a rotating torque.

The stator core 132 illustrated in FIG. 3 is fixedly fitted to theinside of the above-mentioned cylindrical housing 112 by shrink fitting.As a specific assembling manner, for example, the stator core 132 isfirstly arranged, and the stator core 132 is fitted into the housing 112that has been heated and widened the inner diameter by thermal expansionin advance. Subsequently, the housing 112 is cooled to shrink the innerdiameter, to thereby tighten an outer peripheral portion of the statorcore 132 by heat shrink.

The inner diameter of the housing 112 is set to be smaller than theouter diameter of the stator core 132 by a given value so that thestator core 132 does not run idle relative to the housing 112 due to areaction caused by a torque of the rotor 150 during operation. As aresult, the stator core 132 is rigidly fixed to the inside of thehousing 112 by shrink fit. The difference between the outer diameter ofthe stator core 132 and the inner diameter of the housing 112 at roomtemperature is called “fitting margin”. The fitting margin is setassuming a maximum torque of the rotating electric machine 100 wherebythe housing 112 can hold the stator core 132 by a given tighteningforce. The stator core 132 is not only fixedly fitted by shrink fitting,but also may be fixedly fitted into the housing 112 press fitting.

FIG. 5 is a diagram illustrating the rotor 150, which is a diagramillustrating a cross-section of the rotor 150 and the stator 130. Inorder to avoid complication, the stator coil 138 and the insulatingpaper 300 stored within the shaft 118 and the slots 420 are omitted. Asillustrated in FIG. 5, the rotor 150 includes a rotor core 152, andpermanent magnets 154 held in magnet slots formed in the rotor core 152.

The magnet slots each having a cubic shape are formed in the rotor core152 at regular intervals in the circumferential direction in thevicinity of the outer peripheral portion. The permanent magnets 154 areembedded in the respective magnet slots, and fixed thereto by adhesiveor the like. A width of the magnet slots in the circumferentialdirection is formed to be larger than a width of the permanent magnets154 in the circumferential direction, and magnetic gaps 156 are formedon both sides of the permanent magnets 154. The magnetic gaps 156 may beembedded with adhesive, or resin may be solidified integrally with thepermanent magnets 154.

The permanent magnets 154 form a field pole of the rotor 150. In thisembodiment, one permanent magnet 154 is configured to form one magneticpole. Alternatively, one magnetic pole may be configured by a pluralityof permanent magnets. The permanent magnet for forming each magneticpole is increased in multiple with the results that a magnetic fluxdensity of the respective magnetic poles generated by the permanentmagnets is increased so that a magnet torque can be increased.

A magnetization direction of the permanent magnets 154 is oriented alonga radial direction, and an orientation of the magnetization direction isreversed for each of the field poles. That is, when it is assumed thatone surface of the permanent magnet 154 for forming one magnetic pole ona stator side is magnetized to the N pole, and another surface thereofon a shaft side is magnetized to the S pole, one surface of thepermanent magnet 154 for forming an adjacent magnetic pole on the statorside is magnetized to the S pole, and another surface thereof on theshaft side is magnetized to the N pole. In this embodiment, twelvepermanent magnets 154 are arranged at regular intervals in thecircumferential direction so as to be magnetized to alternately changethe magnetization direction for each magnetic pole. As a result, therotor 150 forms twelve magnetic poles.

The permanent magnets 154 may be embedded in the magnet slots of therotor core 152 after the permanent magnets 154 have been magnetized, ormay be inserted into the magnet slots of the rotor core 152 before thepermanent magnets 154 is magnetized, and thereafter magnetized byapplication of a strong magnetic field.

The magnetic force of the permanent magnets 154 that have beenmagnetized is strong, and when the magnet is magnetized before thepermanent magnets 154 are fixed to the rotor 150, a strong attractionforce is generated between the permanent magnets 154 and the rotor core152 when fixing the permanent magnets 154, and the attraction forceinterferes with the operation. Also, dust such as iron powder couldadhere to the permanent magnets 154 due to the strong attraction force.For those reason, it is desirable to magnetize the permanent magnets 154after the permanent magnets 154 have been inserted into the magnet slotsof the rotor core 152 from the viewpoint that the productivity of therotating electric machine 100 is improved. As the permanent magnets 154,a sintered magnet of neodymium series or samarium series, ferritemagnet, or a bond magnet of neodymium series can be used. As a residualmagnetic flux density of the permanent magnets 154 is desirably about0.4 to 1.3 T, the magnet of neodymium series is more proper.

In this embodiment, auxiliary magnet poles 160 are formed between therespective permanent magnets 154 forming the magnetic poles. Theauxiliary magnet poles 160 operate so that a magnetic resistance of aq-axial magnetic flux generated by the stator coil 138 becomes smaller.Then, because the magnetic flux of the q-axial magnetic flux becomes tobe very smaller than the magnetic resistance of the d-axial magneticflux due to the auxiliary magnet poles 160, a large reluctance torque isgenerated.

When a three-phase AC current is supplied to the stator coil 138 togenerate the rotating magnetic field in the stator 130, the rotatingmagnetic field is exerted on the permanent magnets 154 of the rotor 150and the magnet torque is generated. Since the above-mentioned reluctancetorque is generated in the rotor 150 in addition to the magnet torque,both of the above-mentioned magnet torque and reluctance torque areexerted on the rotor 150 as the rotating torque, thereby being capableof obtaining a large rotating torque.

(Description of Rotor Coil)

FIG. 6 is a perspective view illustrating the stator coil 138 for threephases. The stator coil 138 is connected with the configuration of astar connection as illustrated in FIG. 7. In this embodiment, there isapplied the stator coil 138 having the two-star configuration in whichtwo star connections are connected in parallel. That is, the two-starconfiguration includes a star connection of a U1 phase, a V1 phase, anda W1 phase, and a star connection of a U2 phase, a V2 phase, and a W2phase. Lead wires of the U1 and U2 phases are collected into one pieceby an AC terminal 41U, lead wires of the V1 and V2 phases are collectedinto one piece by an AC terminal 41V, and lead wires of the W1 and W2phases are collected into one piece by an AC terminal 41W. N1 and N2 areneutral points of the respective star connections.

Also, the stator coil 138 is winded in a distributed winding system. Thedistributed winding is a winding system in which phase winding coils arewinded on the stator core 132 so that the phase wining coils are storedin two of the slots 420 which are distant from each other over theplurality of slots 420. This embodiment has a featured that since thedistributed winding is applied as the winding system, the developedmagnetic flux distribution is closer to a sine wave than that of aconcentrated winding, and the reluctance torque is easily generated. Forthat reason, the rotating electric machine 100 improves in thecontrollability of a field-weakening control and a control utilizing thereluctance torque, is available over a wide rotating speed range from alow rotating speed to a high rotating speed, and can obtain excellentmotor characteristics suitable for an electric vehicle.

The stator coil 138 may be circular or square in cross-section. Astructure in which an inner cross-section of the slots 420 is used asefficiently as possible, and spaces within the slots are reduced tendsto lead to an improvement in the efficiency. Therefore, the square shapein cross-section is desirable from the viewpoint of an improvement inthe efficiency. The square shape in cross-section of the stator coil 138may be shorter in the circumferential direction of the stator core 132,and longer in the radial direction. Conversely, the square shape may belonger in the circumferential direction, and shorter in the radialdirection. In this embodiment, the stator coil 138 is formed of arectangular coil in which a rectangular cross-section of the stator coil138 within each of the slots 420 is longer in the circumferentialdirection of the stator core 132, and shorter in the radial direction ofthe stator core 132. Also, an outer periphery of the rectangular coil iscovered with an insulation coat.

In the stator coil 138 illustrated in FIG. 6, as illustrated in FIG. 2,coils of six systems (U1, U2, V1, V2, W1, W2) in total are loaded inclose contact with the stator core 132. The coils of the six systemsconfiguring the stator coil 138 are arranged at mutually properintervals by the slots 420. As illustrated in FIG. 6, the AC terminals41U, 41V, and 41W which are respective input/output terminals of thethree phases of U, V, and W, and neutral wire connection portions 711and 712 are arranged on one coil end 140 a side of the stator coil 138.

In order to improve the workability in assembling the rotating electricmachine 100, the AC terminals 41U, 42V, and 43W for receiving thethree-phase AC power are arranged to be protruded from the coil end 140a outward in the axial direction of the stator core 132. The stator 130is connected to a power conversion device not shown through the ACterminals 41U, 42V, and 43W to supply the AC power.

As illustrated in FIGS. 2 and 6, the coil ends 140 a and 140 b which areportions protruded from the stator core 132 outward in the axialdirection are arranged in order as a whole, and the overall rotatingelectric machine is downsized. Also, the arrangement of the coil ends140 a and 140 b in order is desirable from the viewpoint of animprovement in the reliability of the insulation characteristic.

FIG. 8 is a perspective view illustrating the stator coil 138U of the Uphase winded on the stator core 132. FIGS. 9 and 10 are perspectiveviews illustrating the stator coil 138U1 of the U1 phase, and the statorcoil 138U2 of the U2 phase, which configure the stator coil 138U. As isapparent from FIGS. 9 and 10, the stator coil 138 is formed of a segmentcoil in which the plurality of segment coils 28 each having the U-shapedwire is connected to each other. The segment coils 28 each have a topportion 28 c arranged on one coil end 140 a. Also, both ends 28E of onesegment coil 28 are connected to another segment coil 28 on the othercoil end 140 b.

FIG. 11 is a diagram illustrating a connection method of the segmentcoil 28. The segment coils 28 which have not yet been loaded into theslots 420 of the stator core 132 are each formed of a U-shaped wireincluding a chevron top portion 28 c and straight portions 28 b asillustrated in an upper side of the figure. Each of the segment coils 28is inserted into the slot 420 from the coil end 140 a side (refer toFIG. 2) of the stator core 132. After the segment coils 28 have beeninserted into the slots 420, each of the straight portions 28 bprotruded from the stator core 132 to the opposite side (coil end 140 bside in FIG. 2) is bent in a direction of the adjacent segment coil tobe connected, and an end 28E thereof is bent downward in the figure.Then, the end 28E, and an end 28E of the adjacent segment coil 28 areconnected to each other by welding.

In this way, the main coil having the plurality of segment coils 28connected to each other is formed. Then, a sub-coil including the leadwire and a sub-coil including the neutral wire are connected to bothends of the main coil configured by the segment coils 28 to form onephase coil. In this way, the main coil is configured by using thesegment coils 28 which are wires formed in advance in, insulationbetween the wires is ensured, and no load is applied to the insulationcoat.

In the stator coil 138U1 of the U1 phase illustrated in FIG. 9, asub-coil 701U1 connected with the AC terminal 41U includes a portionstored in the slots of the stator core 132, and a lead wire 500U1 ledfrom the slots. In the stator coil 138 according to this embodiment, thesub-coil 701U1 is stored in a layer on an outermost peripheral side ofthe slots. The lead wire 500U1 includes a bend 501U1 bent to be curved,and a terminal portion 502U1 connected with the AC terminal 41U. Thesub-coil 701U1 is connected to the end 28E of the segment coil 28disposed on one end of the main coil of the U1 phase on the coil end 140b side. Also, the segment coil 28 disposed on the other end of the maincoil is connected with a sub-coil 702U1 having a neutral wire 711U1.

On the other hand, similarly in the stator coil 138U2 of the U2 phaseillustrated in FIG. 10, a sub-coil 701U2 connected with the AC terminal41U includes a portion stored in the slots of the stator core 132, and alead wire 500U2 led from the slots. The sub-coil 701U2 is stored in alayer on an innermost peripheral side of the slots. The lead wire 500U2includes a bend 501U2 bent to be curved, and a terminal portion 502U2connected with the AC terminal 41U. The bend 501U2 is led in a directionopposite to that of the bend 501U1 of the U1 phase. The sub-coil 701U1is connected to the end 28E of the segment coil 28 disposed on one endof the main coil of the U1 phase on the coil end 140 b side. Also, thesegment coil 28 disposed on the other end of the main coil is connectedwith a sub-coil 702U2 having a neutral wire 712U2.

The terminal portions 502U1 and 502U2 are bent substantiallyperpendicularly to the coil end 140 a in the outer circumferentialdirection of the stator core 132 from the coil end 140 a. Although thedescription will be omitted, the stator coils of the U phase, the Vphase, and the W phase also have the same configuration as the U phasecoil. The stator coils of the U phase, the V phase, and the W phase aredisplaced at given slot pitches in the circumferential direction. Asillustrated in FIG. 6, the AC terminals 41U, 41V, and 41W are arrangedto be concentrated on one portion for connection to the cable, and allarranged in parallel to each other to be oriented in the same direction(direction substantially perpendicular to the coil end 140 a).

The AC terminals 41U, 41V, and 41W are collected in the peripheral widthwithin a given number of slots of the stator core 132. For example, whenthree slots are ensured for each phase in order to ensure mutualinsulation, the AC terminals 41U, 41V, and 41W can be collected in aboutnine slots as a whole, but limited to nine slots. As illustrated in FIG.6, the respective terminal portions of the AC terminals 41U, 41V, and41W are bent so that the respective phases become substantially parallelto each other. Because the respective phases of U, V, and W are arrangedso that the terminal portions are arranged in parallel, the rigidity ofthe terminal portions can be enhanced. In this situation, the terminalportions to which an excessive tension or compression force is appliedare adjacent to each other to absorb the tension and the compressionforce, and the occurrence of fatigue failure in the terminal portionscan be suppressed.

As illustrated in FIG. 6, portions in which the AC terminals 41U, 41V,and 41W are disposed are collected in one place for connection to thecable, and a convex area of the neutral coil routing of the upperportion of the coil end 140 a is narrowed to ensure a gap between theupper portion and an emission portion. Also, a simple structure in whichthe securement of insulation between the wires, and the workability inmanufacturing are taken into account while the AC terminals 41U, 41V,and 41W are concentrated on one place is provided.

Further, as illustrated in FIG. 2, the convex area of the routing of theneutral wire 711 on the coil end 140 a is narrowed to lower the coil end140 a. For that reason, the neutral wires 711U1, 711V1, and 711W1 of theU1 phase, the V1 phase, and the W1 phase are routed on a left side shownin the figure of the AC terminals 41U, 41V, and 41W on the coil end 140a, and connected thereto. On the other hand, the neutral wires 712U2,712V2, and 712W2 of the U2 phase, the V2 phase, and the W2 phase arerouted on a right side shown in the figure of the AC terminals 41U, 41V,and 41W on the coil end 140 a, and connected thereto.

In this embodiment, the lead wires 500U1, 500U2, and the neutral wires711U1, 712U2 which are led from the coil end 140 a are bent so that therouting on the coil end 140 a becomes a shorter route whereby the coilend 140 a and the core back 440 are downsized to reduce the wireresistor. Hereinafter, a bend shape of the lead wires 500U1 and 500U2,and a bend shape of the neutral wires 711U1 and 712U2 will be described.

FIG. 12 is an enlarged view of a portion of the lead wire 500U1illustrated in FIG. 9. The AC terminal 41U is omitted from the figure.The lead wire 500U1 illustrated in FIG. 12 includes a first wire portion511U1, a second wire portion 512U1, and the above-mentioned terminalportion 502U1. The first wire portion 511U1 is a portion risingobliquely upward from a straight (portion inserted into the slot 420) ofthe sub-coil 701U1, and extended to above the top portion 28 c of thesegment coils 28, and creates an arch along the top portion 28 c.

Also, the second wire portion 512U1 is a wire portion routed above theplurality of top portions 28 c (refer to FIG. 6). Since only two segmentcoils are illustrated in FIG. 12, the number of top portions 28 c isalso two. However, in fact, a large number of top portions 28 c arealigned in an arc on the coil end 140 a. Further, the terminal portion502U1 is bent to be curved from the second wire portion 512U1substantially perpendicularly to an outer circumferential direction ofthe coil end 140 a. In the example illustrated in FIG. 12, the terminalportion 502U1 rises upward from the second wire portion 512U1 once sothat wide surfaces of the rectangular wire are oriented vertically, andthen is bent in the outer circumferential direction.

In this embodiment, a forming process (automatic forming process) isused for forming the lead wire 500U1 having a complicated shape asillustrated in FIG. 12. Up to now, the forming process was not used forforming the rectangular wire having the insulation coat, but die formingwas used to form the rectangular wire into a more simplified shape. Inthe forming of the segment coils 28, forming using a die is used as inthe conventional art.

FIGS. 13 and 14 are diagrams illustrating the forming press of the leadwire 500U1. FIG. 13 is a diagram viewed from a center side of the statorcore 132, and FIG. 14 is a diagram viewed from above of the coil end 140a along the axial direction. As understood from FIGS. 13 and 14, thelead wire 500U1 is bent sterically (three-dimensionally), and it is verydifficult to form such shape with the use of the die.

In the example illustrated in FIGS. 13 and 14, the bending process usingthe forming process is conducted in the order of FIGS. 13, 14(a), and14(b). P1 to P12 indicate positions of the molding pins when conductingthe forming process. The bending process is conducted in the order to P1to P12. In FIG. 13, the pins are abutted against narrow surfaces of therectangular wire to conduct the bending process. The sub-coil 701U1 isbent in the order of the pin positions P1, P2, and P3 to form the firstwire portion 511U1, the second wire portion 512U1, and the terminalportion 502U1.

Subsequently, in FIG. 14, the pins are abutted against the wide surfacesof the rectangular wire to conduct the bending process. The sub-coil701U1 is bent in the order of the pin positions P4, P5, P6, P7, and P8to form a final shape of the first wire portion 511U1. The first wireportion 511U1 is curved in the radial direction of the coil end. Then,the first wire portion 511U1 is bent in the order of the pin positionsP9, P10, and P11 to form a final shape of the second wire portion 512U1.Finally, the first wire portion 511U1 is bent at 90 degrees in the pinposition P12 to form a portion of the terminal portion 502U1.

In this way, because the lead wire 500U1 is bent by the forming process,as illustrated in FIG. 12, the lead wire 500U1 includes a plurality ofbends B against which the molding pins are abutted, and straights Sbetween one bend B and an adjacent bend B. The pin abutted portions ofthe bends B are formed with impressions of the molding pins. When theplurality of bending is thus conducted, even if the bend 501U1 has acomplicated curved shape, the bend 501U1 can be approximated by apolygonal line with high precision. At least two bends B are formed inthe second wire portion 512U1 routed to be curved in the vicinity of thetop portion of the coil end 140 a so as to more approximate an idealshape.

FIG. 15 illustrates the lead wire 500U1 of the U1 phase coil and thelead wire 500U2 of the U2 phase coil. The terminal portion 502U1 of thelead wire 500U1 and the terminal portion 502U2 of the lead wire 500U2are connected to the AC terminal 41U in common. Because of arelationship of the arrangement of the AC terminal 41U, lengths of thelead wires 500U1 and 500U2 are different from each other. Also, since aroute position is different between the bend 501U1 and the bend 501U2,the bend shape is also different from each other. As illustrated in FIG.15, since a shape in which the lead wire 500U1 of the U1 phase coil andthe lead wire 500U2 of the U2 phase coil are connected to each other bythe AC terminal 41U is trapezoidal, the rigidity can be enhanced. As aresult, a natural frequency of the coil per se can be reduced ascompared with a cantilever structure.

FIG. 16 is a diagram illustrating a portion of the neutral wireconnection portion 712 in FIG. 6. The neutral wire connection portion712 is a portion in which the neutral wire 712U2 of the U2 phase, theneutral wire 712V2 of the V2 phase, and the neutral wire 712W2 of the W2phase are connected to each other, which is a portion corresponding tothe neutral point N2 in FIG. 7. Because the slots into which thesub-coils 702U2, 702V2, and 702W2 of the U2, V2, and W2 phases areinserted are displaced from each by a given slot interval, the lengthsof the neutral wires 712U2, 712V2, and 712W2 are different according tothe displacement, and the shapes of them are also different from eachother.

If the AC terminal 41U is connected as illustrated in FIG. 15, aninsulation coat 600 is formed on the bends 501U1 and 501U2 which areportions led from the slots of the sub-coils 701U1 and 701U2, therebyensuring a sufficient withstand voltage in those portions. Theinsulation coat 600 is properly formed of, for example, an insulatingpowder coating film. As a coating material (powder) used for insulatingpower coating, an insulating epoxy resin or the like is used. Likewise,if the three neutral wires 712U2, 712V2, and 712W2 are connected to eachother as illustrated in FIG. 16, the insulation coat 600 is formed onthe portion to which those neutral wires are led as illustrated in FIG.18.

Second Embodiment

FIGS. 19 and 20 illustrate a second embodiment of the present invention.In the above-mentioned first embodiment, the stator coil 138 is of atwo-star connection structure. On the other hand, in the secondembodiment, the same segment coil 28 is of a one-star connectionstructure as illustrated in FIG. 19. When the U phase coil is viewed,the coils indicated by symbols U1 and U2 have the same configuration asthat of the U1 phase coil and the U2 phase coil illustrated in FIG. 7,and the coil U1 and the coil U2 are connected to each other by a bridgewire 400U. The same is applied to the V phase and the W phase. The Uphase, V phase, and W phase coils connected by the bridge wires 400U,400V, and 400W are connected to each other at the neutral point N.

FIG. 20 illustrates the bridge wire 400U, and the bridge wires 400U and400W also have the same structure as that of the wire 400U. In thisexample, the bridge wire 400U will be typically described. The bridgewire 400U includes straight wire portions 703 a and 703 b inserted intothe slots, and a coupling portion 500 that connects those straight wireportions 703 a and 703 b. Also, the coupling portion 500 is a portionled to the outside of the slots, and includes oblique portions 500 a and500 b which are lead portions from the slots, and a route portion 500 cthat is routed on the coil end. The oblique portions 500 a and 500 b arearranged in gaps of the segment coils 28 group.

The wire led from the straight wire portion 703 b as indicated by theoblique portion 500 b is bent in an opposite direction, and thereafterconnected to the oblique portion 500 a. In this embodiment, the formingprocess is applied to the formation of the coupling portion 500 of thebridge wire 400U in addition to the lead wire and the neutral wiredescribed in the first embodiment. In the bridge wire 400U thus havingthe complicated shape, the coupling portion 500 formed by a polygonalline close to an ideal line can be easily obtained by the formingprocess. That is, the coupling portion 500 is configured by straightsand bends.

The above-mentioned embodiment has the operation and effects describedbelow.

(1) As illustrated in FIGS. 6, 8, 9, and 10, the stator coil 138U1includes: the main coils in which the plurality of segment coils 28 eachhaving the rectangular cross-section wire formed into the substantiallyU-shaped wire in advance is connected to each other; the sub-coil 701U1having the lead wire 500U1 led from the slot 420 and attached with theAC terminal 41U, and connected to one end of the respective main coils;and the sub-coil 702U1 having the neutral wire 711U1 led from the slots,and connected to the other end of the respective main coils. The statorcoil 138 illustrated in FIG. 6 has six sets of the above phase coils ofU1, U2, V1, V2, W1, and W2. For example, the lead wire 500U1 of thesub-coil 701U1 and the neutral wire 711U1 of the sub-coil 702U1 areconfigured by the wire with a bend structure having the plurality ofstraights S and bends B.

The lead wire 500U1 and the neutral wire 711U1 are each formed of thewire having the bend structure, thereby making it easy to allow theshapes of the lead wire 500U1 and the neutral wire 711U1 to approximateideal shapes respectively. As a result, a useless routing can besuppressed, and a reduction in the coil usage and a reduction in thewire resistor can be conducted. Also, the routing on the coil end 140 ais downsized, and the coil end 140 a and the core back 440 can bereduced.

(2) Further, the lead wire 500U1 includes the first wire portion 511U1that is the first wire area led from the slots and arriving at the topportion 28 c of the segment coils 28, the terminal portion 502U1 that isthe terminal connection area disposed at the head of the lead wireleading portion, and the second wire portion 512U1 which is the coil endroute area between the terminal portion 502U1 and the first wire portion511U1. Then, the second wire portion 512U1 is bent sterically so as toform two or more bends B, thereby allowing the shape of the second wireportion 512U1 routed on the coil end 140 a to approximate the idealshape. As a result, an increase in the height of the overall coil end byrouting the lead wire 500U1 can be suppressed.

(3) Also, in the case of the wire structure using the bridge wires 400Uto 400W illustrated in FIG. 19, as illustrated in FIG. 20, the couplingportion 500 is configured by the wire with the bend structure having theplurality of straights and bends, thereby allowing the shape of the wirerouted on the coil end to approximate the ideal shape, and the overallcoil end can be prevented from being upsized.

(4) The bends are formed by the forming process for bending the wirewhile abutting the molding pin against the wire. The bend structure canbe easily formed by using an automatic forming machine. When the formingprocess is conducted, the impression by the molding pin is formed in thebends on the wire surface. The total number of segment coils 28 islarge, but classified into several kinds of shapes. Also, because theshape is relatively simple, it is suitable to use the forming using thedie as in the conventional art from the viewpoints of the costs. On theother hand, the number of lead wires and neutral wires is 12 at themaximum even in the stator coil of the two-star connection, and theshapes are different from each other. For that reason, it will be veryexpensive to form the respective wires by the die.

On the other hand, when the lead wires and the neutral wires are bent bythe forming process, this process easily deals with any shape, and thewires can be freely formed into an arbitrary shape. Further, the aboveprocess is divided into the process of forming the lead wires and theneutral wires with the use of NC forming, and the process of forming theplurality of segment coils by the die, thereby being capable ofenhancing the productivity. Also, the coils having the stable shape canbe manufactured with a reduction in the die.

(5) All of bend radii of the bends have the same dimension whereby thebending process can be sequentially conducted with the same molding pin,and the setup of the pin exchange can be omitted with the results thatthe productivity can be improved. Also, the bends have the same bendwhereby the enamel coat of the coil can be evenly damaged, and the coilexcellent in the insulation is obtained.

(6) Further, the insulation coat 600 is formed on the wire area wherethe straights and the bends are formed, thereby obtaining the sufficientwithstand voltage in cooperation with the insulation coat of the wire.

(7) Also, the stator coil 138 has a coil structure in which the leadwire and the neutral wire are led from an innermost peripheral side oran outermost peripheral side of the slots. With this configuration, thelead wires and the neutral wires can be easily routed, and the lengthsthereof can be suppressed. Also, the coil end 140 a and the core back440 can be reduced. This embodiment provides the coil structure in whichthe lead wires 41U, 41V1, and 41W are aligned perpendicularly to theaxial direction and in parallel to each other, and the neutral wires 711and 712 are arranged in opposite directions outwardly in thecircumferential direction of the lead wires 41U, 41V1, and 41W (refer toFIG. 6). With the above structure, the lead wires and the neutral wiresare led from the innermost peripheral side or the outermost peripheralside of the slots. Also, the convex area of the routing is narrowed toensure the gap between the convex area and the mission portion. Also, asimple structure in which the securement of insulation between thewires, and the workability in manufacturing are taken into account whilethe lead wires are concentrated on one place is provided.

The above description is exemplary, and the interpretation of thepresent invention is not limited and detained by correspondencerelationships between the description of the above embodiments and thedefinitions of the claims. The other examples without departing from thetechnical concept of the present invention are included in the presentinvention. For example, in the above-mentioned embodiments, the rotatingelectric machine having the permanent magnet in the rotor has beenexemplified. Likewise, the present invention can be applied to thestator of the rotating electric machine such as an induction motor.Also, the present invention can be applied to a device other than therotating electric machine for driving the vehicle.

The disclosure of the following basic priority application isincorporated herein by reference in its entirety.

Japanese Patent Application No. 2011-207403 (filed on Sep. 22, 2011).

The invention claimed is:
 1. A stator for a rotating electric machinecomprising: a stator core having a plurality of slots aligned along acircumferential direction; and a stator coil with an insulation coatinserted into the slots of the stator core; wherein the stator coilincludes: main coils of a plurality of phases in which a plurality ofsegment coils each having a rectangular cross-section wire formed into asubstantially U-shaped wire in advance is connected to each other; firstsub-coils each having a lead wire led from the slots and attached withan AC terminal, and connected to one end of the respective main coils;and second sub-coils each having a neutral wire led from the slots, andconnected to the other end of the respective main coils; wherein thelead wire and the neutral wire are each formed of a wire with a bendstructure having a plurality of straights and bends; wherein particularslots of the slots into which the respective second sub-coils areinserted are displaced from each other by a given slot interval; whereinthe bends are formed on a coil end of the stator coil; wherein the maincoil of each phase is configured by connecting two divided main coils toeach other by a bridge coil; wherein the bridge coil includes aconnection area led to an external of the slots over two of the slots;and wherein the connection area is formed of a wire with a bendstructure having a plurality of straights and bends.
 2. A stator for arotating electric machine comprising: a stator core having a pluralityof slots aligned along a circumferential direction; and a stator coilwith an insulation coat inserted into the slots of the stator core;wherein the stator coil includes: main coils of a plurality of phases inwhich a plurality of segment coils each having a rectangularcross-section wire formed into a substantially U-shaped wire in advanceis connected to each other; first sub-coils each having a lead wire ledfrom the slots and attached with an AC terminal, and connected to oneend of the respective main coils; and second sub-coils each having aneutral wire led from the slots, and connected to the other end of therespective main coils; wherein the lead wire and the neutral wire areeach formed of a wire with a bend structure having a plurality ofstraights and bends; wherein particular slots of the slots into whichthe respective second sub-coils are inserted are displaced from eachother by a given slot interval; wherein the bends are formed on a coilend of the stator coil; and wherein an enamel coating is formed on awire area where the straights and the bends are formed.